Is it ok to run the front 2 channels of a 4 channel amp at a 4 ohm load and have the rear 2 channels at a 2 ohm load? Does this effect the amp in any way or does it really not matter? Reason being is, I've got components in the front doors, then I've got coax speakers in my rear walls and in my hatch area below the glass. So I'm running 4 speakers in the rear.